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Ultimate Spatial Resolution Realisation in Optical Frequency Domain Reflectometry with Equal Frequency Resampling. SENSORS 2021; 21:s21144632. [PMID: 34300374 PMCID: PMC8309478 DOI: 10.3390/s21144632] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 11/17/2022]
Abstract
A method based on equal frequency resampling is proposed to suppress laser nonlinear frequency sweeping for the ultimate spatial resolution in optical frequency domain reflectometry. Estimation inaccuracy of the sweeping frequency distribution caused by the finite sampling rate in the auxiliary interferometer can be efficiently compensated by the equal frequency resampling method. With the sweeping range of 130 nm, a 12.1 µm spatial resolution is experimentally obtained. In addition, the sampling limitation of the auxiliary interferometer-based correction is discussed. With a 200 m optical path delay in the auxiliary interferometer, a 21.3 µm spatial resolution is realised at the 191 m fibre end. By employing the proposed resampling and a drawing tower FBG array to enhance the Rayleigh backscattering, a distributed temperature sensing over a 105 m fibre with a sensing resolution of 1 cm is achieved. The measured temperature uncertainty is limited to ±0.15 °C.
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Wei X, Hormel TT, Jia Y. Phase-stabilized complex-decorrelation angiography. BIOMEDICAL OPTICS EXPRESS 2021; 12:2419-2431. [PMID: 33996238 PMCID: PMC8086438 DOI: 10.1364/boe.420503] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/20/2021] [Accepted: 03/23/2021] [Indexed: 06/12/2023]
Abstract
In this study, we developed a novel phase-stabilized complex-decorrelation (PSCD) optical coherence tomography (OCT) angiography (OCTA) method that can generate high quality OCTA images. This method has been validated using three different types of OCT systems and compared with conventional complex- and amplitude-based OCTA algorithms. Our results suggest that in combination with a pre-processing phase stabilization method, the PSCD method is insensitive to bulk motion phase shifts, less dependent on OCT reflectance than conventional complex methods and demonstrates extended dynamic range of flow signal, in contrast to other two methods.
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Affiliation(s)
- Xiang Wei
- Casey Eye Institute, Oregon Health and Science University, Portland, Oregon 97239, USA
- Department of Biomedical Engineer, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - Tristan T. Hormel
- Casey Eye Institute, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - Yali Jia
- Casey Eye Institute, Oregon Health and Science University, Portland, Oregon 97239, USA
- Department of Biomedical Engineer, Oregon Health and Science University, Portland, Oregon 97239, USA
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Zavareh AT, Hoyos S. Kalman-Based Real-Time Functional Decomposition for the Spectral Calibration in Swept Source Optical Coherence Tomography. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2020; 14:257-273. [PMID: 31751249 DOI: 10.1109/tbcas.2019.2953212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This paper presents a real-time functional decomposition adaptive algorithm for the optimal sampling of the interferometric signal in Swept-Source Optical Coherence Tomography imaging systems, which completely eliminates the input signal dependent nonlinearities that are problematic in current state-of-the-art OCT realizations that use interpolation and resampling. The proposed adaptive calibration algorithm uses the Kalman approach to estimate the wavenumber index parameter k from the Mach-Zender Interferometer signal which is then applied to an adaptive level crossing sampler to generate a sampling clock that k-linearizes the data on real-time during the sampling process. Such a system implements an artifact-free realization of the technology removing the need for classical interpolation and resampling. The new real-time linearization scheme has the additional capability of increasing the imaging acquisition speed by 10X while providing robustness to noise, properties that are demonstrated through mathematical analysis and simulation results throughout the paper.
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Ling Y, Meiniel W, Singh-Moon R, Angelini E, Olivo-Marin JC, Hendon CP. Compressed sensing-enabled phase-sensitive swept-source optical coherence tomography. OPTICS EXPRESS 2019; 27:855-871. [PMID: 30696165 PMCID: PMC6410915 DOI: 10.1364/oe.27.000855] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/30/2018] [Accepted: 12/21/2018] [Indexed: 05/21/2023]
Abstract
Here we present a novel phase-sensitive swept-source optical coherence tomography (PhS-SS-OCT) system. The simultaneously recorded calibration signal, which is commonly used in SS-OCT to stabilize the phase, is randomly sub-sampled during the acquisition, and it is later reconstructed based on the Compressed Sensing (CS) theory. We first mathematically investigated the method, and verified it through computer simulations. We then conducted a vibrational frequency test and a flow velocity measurement in phantoms to demonstrate the system's capability of handling phase-sensitive tasks. The proposed scheme shows excellent phase stability with greatly discounted data bandwidth compared with conventional procedures. We further showcased the usefulness of the system in biological samples by detecting the blood flow in ex vivo swine left marginal artery. The proposed system is compatible with most of the existing SS-OCT systems and could be a preferred solution for future high-speed phase-sensitive applications.
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Affiliation(s)
- Yuye Ling
- Department of Electrical Engineering, Columbia University, 500 W 120th St., New York, New York 10027,
USA
| | - William Meiniel
- Institut Mines-Telecom, Telecom-ParisTech, CNRS LTCI, Paris,
France
- Institut Pasteur, BioImage Analysis unit, CNRS UMR 3691, Paris,
France
| | - Rajinder Singh-Moon
- Department of Electrical Engineering, Columbia University, 500 W 120th St., New York, New York 10027,
USA
| | - Elsa Angelini
- Institut Mines-Telecom, Telecom-ParisTech, CNRS LTCI, Paris,
France
- NIHR Imperial BRC, ITMAT Data Science Group, Imperial College, London,
United Kingdom
- Department of Biomedical Engineering, Columbia University, 500 W 120th St., New York, New York 10027,
USA
| | | | - Christine P. Hendon
- Department of Electrical Engineering, Columbia University, 500 W 120th St., New York, New York 10027,
USA
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Moon S, Chen Z. Phase-stability optimization of swept-source optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2018; 9:5280-5295. [PMID: 30460128 PMCID: PMC6238911 DOI: 10.1364/boe.9.005280] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 09/21/2018] [Accepted: 09/25/2018] [Indexed: 05/18/2023]
Abstract
Phase-resolved imaging of swept-source optical coherence tomography (SS-OCT) is subject to phase measurement instabilities involved with the sweep variation of a frequency-swept source. In general, optically generated timing references are utilized to track the variations imposed on OCT signals. But they might not be accurately synchronized due to relative time delays. In this research, we investigated the impact of the signal delays on the timing instabilities and the consequent deviations of the measured phases. We considered two types of timing signals utilized in a popular digitizer operation mode: a sweep trigger from a fiber Bragg grating (FBG) that initiates a series of signal sampling actions clocked by an auxiliary Mach-Zehnder interferometer (MZI) signal. We found that significant instabilities were brought by the relative delays through incoherent timing corrections and timing collisions between the timing references. The best-to-worst ratio of the measured phase errors was higher than 200 while only the signal delays varied. Noise-limited phase stability was achieved with a wide dynamic range of OCT signals above 50 dB in optimized delays. This demonstrated that delay optimization is very effective in phase stabilization of SS-OCT.
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Affiliation(s)
- Sucbei Moon
- Beckman Laser Institute, University of California, Irvine, Irvine, CA 92617, USA
- Department of Physics, Kookmin University, Seoul 02707, South Korea
| | - Zhongping Chen
- Beckman Laser Institute, University of California, Irvine, Irvine, CA 92617, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA
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KIM WIHAN, KIM SANGMIN, OGHALAI JOHNS, APPLEGATE BRIANE. Endoscopic optical coherence tomography enables morphological and subnanometer vibratory imaging of the porcine cochlea through the round window. OPTICS LETTERS 2018; 43:1966-1969. [PMID: 29714773 PMCID: PMC6731066 DOI: 10.1364/ol.43.001966] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 03/19/2018] [Indexed: 05/21/2023]
Abstract
A highly phase stable hand-held (HH) endoscopic system has been developed for optical coherence tomography and vibrometry. Designed to transit the ear canal to the middle ear space and peer through the round window (RW), it is capable of imaging the vibratory function of the cochlear soft tissues with subnanometer scale sensitivity. A side-looking, 9 cm long rigid endoscope with a distal diameter of 1.2 mm, was able to fit within the RW niche and provide imaging access. The phase stability was achieved in part by fully integrating a Michelson interferometer into the HH device. Ex vivo imaging of a domestic pig demonstrated the system's ability for functional vibratory imaging of the cochlea via the RW.
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Affiliation(s)
- WIHAN KIM
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - SANGMIN KIM
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - JOHN S. OGHALAI
- Caruso Department of Otolaryngology–Head and Neck Surgery, University of Southern California, Los Angeles, CA 90089, USA
| | - BRIAN E. APPLEGATE
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
- Corresponding author:
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